Literary devices or poetic devices are used by an author to compare unlike ideas, create imagery or symbolism, or to exaggerate ideas through such techniques as: metaphors, similes, alliteration, hyperbole, personification, and irony.
Ironically, the poem itself speaks to the "nots" of what the narrator's love is like physically to show the opposite of what the narrator's love is like.
In "Sonnet 130", Shakespeare uses the following devices:
Assonance- repetition of vowel sound in a line (here, the sound "I")
If snow be white, why then her breasts are dun;
Alliteration- repetition of a consonant sound in a line of poetry (here, the sound "h")
I love to hear her speak
William Shakespeare's Sonnet 130, "My mistress' eyes are nothing like the sun," displays a variety of literary devices. The very term sonnet suggests on important group of literary devices, namely meter and rhyme. As is common with the English, or Shakespearean, sonnet, the poem consists of fourteen lines of iambic pentameter rhymed ABAB CDCD EFEF GG. There are several uses of assonance, especially long vowels in the middle of lines that echo the vowels of nearby rhyme words such as "reeks ... speak".
The next common device used in the poem is metaphor. While in the traditional Petrarchan or Italian sonnet, metaphors are used to amplify the beauties of the beloved, Sonnet 130 is an "anti-Petrarchan" sonnet, and the metaphors often act to parody the exaggerations of the Italian tradition, and create a sense of realism. Such metaphors include the description of hair as "black wires" and cheeks as "dun" when compared to roses.
As discussed above, another device used is parody, in which the poet satirizes existing conventions in order to make his point.
The main literary device employed with Sonnet 130 is that of parody, In this sonnet, Shakespeare flaunts the blazon, a literary poem that praises the lover by cataloging the virtues and other sterling characteristics of the beloved. Thus, this anti-Petrarchan comparison offers a touch of humor to Shakespeare's sonnet sequence as the mistress is far from being a goddess or ideal.
If hairs be wires, black wires grow on her head
I have seen roses damask'd, red and white,
But no such roses see I in her cheeks....
Here, too, in this sonnet Shakespeare mocks, or parodies, the conventions of the sonnet sequence in which there are three separate quatrains, which often are formed around a separate metaphor with a closing couplet that ties all ideas together. For, in Sonnet 130, the metaphors are in the negative and their crescendo is toward the worse rather than waxing superlative. For, the mistress's breasts are "dun," her hair like "wire," her breath "reeks," her voice is abrasive, and she "treads on the ground" like the mechanicals of A Midsummer Night's Dream. Finally, rather than tying the ideas together in the couplet, the poet offers a contradiction with his simile,
And yet, by heaven, I think my love as rare
As any she belied with false compare.